Structures of ordered alloys with hexagonal close packing

In the framework of non-model thermodynamics ordering type transitions into interstitial phases in multicomponent alloys with hexagonal close packing are discussed. Ordered phase structures characterized by vectors K, possessing an isolated symmetry in the reciprocal lattice are described. The ordering transition parameters which are discussed in this work are transformed by irreducible representations including representations which do not meet the Lifshitz criterion. The method applied enables one to discuss transitions of both the second and first orders. As an example of the application of the results of this work, a number of familiar interstitial structures are analyzed.